diff --git a/lib/private/legacy/image.php b/lib/private/legacy/image.php
index 5403cccd02..47f2a977e9 100644
--- a/lib/private/legacy/image.php
+++ b/lib/private/legacy/image.php
@@ -747,7 +747,7 @@ class OC_Image implements \OCP\IImage {
 							$this->logger->warning($error, array('app' => 'core'));
 							return $im;
 						}
-						$color = unpack('V', $part . $vide);
+						$color = @unpack('V', $part . $vide);
 						break;
 					case 16:
 						if (!($part = substr($data, $p, 2))) {
@@ -755,20 +755,20 @@ class OC_Image implements \OCP\IImage {
 							$this->logger->warning($error, array('app' => 'core'));
 							return $im;
 						}
-						$color = unpack('v', $part);
+						$color = @unpack('v', $part);
 						$color[1] = (($color[1] & 0xf800) >> 8) * 65536 + (($color[1] & 0x07e0) >> 3) * 256 + (($color[1] & 0x001f) << 3);
 						break;
 					case 8:
-						$color = unpack('n', $vide . substr($data, $p, 1));
-						$color[1] = $palette[$color[1] + 1];
+						$color = @unpack('n', $vide . substr($data, $p, 1));
+						$color[1] = (isset($palette[$color[1] + 1])) ? $palette[$color[1] + 1] : $palette[1];
 						break;
 					case 4:
-						$color = unpack('n', $vide . substr($data, floor($p), 1));
+						$color = @unpack('n', $vide . substr($data, floor($p), 1));
 						$color[1] = ($p * 2) % 2 == 0 ? $color[1] >> 4 : $color[1] & 0x0F;
-						$color[1] = $palette[$color[1] + 1];
+						$color[1] = (isset($palette[$color[1] + 1])) ? $palette[$color[1] + 1] : $palette[1];
 						break;
 					case 1:
-						$color = unpack('n', $vide . substr($data, floor($p), 1));
+						$color = @unpack('n', $vide . substr($data, floor($p), 1));
 						switch (($p * 8) % 8) {
 							case 0:
 								$color[1] = $color[1] >> 7;
@@ -795,7 +795,7 @@ class OC_Image implements \OCP\IImage {
 								$color[1] = ($color[1] & 0x1);
 								break;
 						}
-						$color[1] = $palette[$color[1] + 1];
+						$color[1] = (isset($palette[$color[1] + 1])) ? $palette[$color[1] + 1] : $palette[1];
 						break;
 					default:
 						fclose($fh);